Does CPP tank fix fueling overflow problems or is it the filler tube design or.......

[Bihili]

I am tired of spilling gasoline on my car when refueling.
It is almost impossible to hold the nozzle on super slow and not spill gas.
With an original tank I am thinking about changing to either the CPP 25 or 29 gallon tank but
will I have the same refueling problem?
It looks like to me the problem is with the design of the venting tube.
I put in a butterfly check valve in the filler tube to prevent back flow on acceleration but it does nothing to help filling up at the gas station.
This has been discussed several times at other forums but i have not seen a solution.
Yes I know today's pumps are much faster BUT.....
What do you think is the cause and will the CPP tank cure it??

[markm]

I am tired of spilling gasoline on my car when refueling.
It is almost impossible to hold the nozzle on super slow and not spill gas.
With an original tank I am thinking about changing to either the CPP 25 or 29 gallon tank but
will I have the same refueling problem?
It looks like to me the problem is with the design of the venting tube.
I put in a butterfly check valve in the filler tube to prevent back flow on acceleration but it does nothing to help filling up at the gas station.
This has been discussed several times at other forums but i have not seen a solution.
Yes I know today's pumps are much faster BUT.....
What do you think is the cause and will the CPP tank cure it??

I have the same problem with my 55 and 56, never owned a 57 or even ridden in one that I recall so I dont know if they have this issue. They do have a vent line on tanlk that 55/56 does not have. I dont believe a bigger tank will help unless it has different venting.

[chevynut]

I think the cause of the problem is that as gas enters the tank through the filler neck, it forces air out of the tank and back up the filler neck. This air tries to push the gas back out of the filler neck. I thought the 57 vent hose was designed to prevent that from happening. But keep in mind that it vents air back to a location below the filler opening. If your "butterfly" is above that, the air can't escape so your vent doesn't work correctly. I'd remove the butterfly and try it.

Not sure why this doesn't occur on newer vehicles, unless they're vented better somehow....

In retrospect, I am thinking maybe I should have installed a larger filler tube than stock on my Nomad. I didn't add a vent hose like the 57's have, but I still may do that.

[chevynut]

Oh, and I don't think the larger tank will cure the problem if you still use the stock filler neck or they vent it some other way.

[chevynut]

It looks like virtually all newer cars have vented filler tubes....

http://www.fillernecksupply.com/servlet/StoreFront

[Bihili]

The butterfly check valve is below upper filler tube inside the connecting rubber hose, I don't think it is the cause.
This seems to be a problem on all 55,56 & 57's.

Could the slope of the filler tube cause the problem?

[chevynut]

Make sure that your vent tube is connected, not kinked, and open all the way down to the tank. I personally don't think the slope of the tube is the problem. Seems like your vent isn't working like it's supposed to.

[markm]

Make sure that your vent tube is connected, not kinked, and open all the way down to the tank. I personally don't think the slope of the tube is the problem. Seems like your vent isn't working like it's supposed to.

Back in the early 80s when I took the 9 inch out of my 67 Camaro and installed a 12 bolt posi and really started hooking up I used to toss gas out the stock SS gas cap. I fixed the problem by removing the sender and drilling a hole in it and brazing a piece of 3/16 brake linne in. The line had a couple loops and ran to the atmosphere. I have wondered if this would help this issue.

[chevynut]

The butterfly check valve is below upper filler tube inside the connecting rubber hose, I don't think it is the cause.
This seems to be a problem on all 55,56 & 57's.

If the butterfly valve is below the upper filler tube, how does the gas nozzle push it open? If it doesn't, how does fuel get past it easily? I assume it's spring loaded....in any case it can't HELP fuel go into the tank. I think that's your problem. I'd take it out.

'55s and '56s have the problem because their filler necks aren't vented like the '57s. I don't think it should be happening on a '57.

[Bihili]

I made the check valve and it is similar to: http://www.classicchevy.com/chevy-gas-filler-neck-valve-one-way-1956-1957.html


I will pull the vent hose off and double check it.
Maybe I overlooked the vent tube when it was sandblasted and it's plugged.